Metal-pickling process.



description of the same.

lowed to st'and'inwater (preferably heated centrated acid becoming diluted loses its substances are carbonized and the articles concentration is that of the common comarticles a long time in relatively cold conkling THOMAS REGINALD Davrnson, or wEs'rmoUNr, QUEBEC, Genera.

mnrALrIonrne raooass.

No Drawing.

Specification of l 'ietters Patent.

Application filed July 11, 1913. Serial No. 778,575.

Fatented July 21, 1914.

To all whom it may concern Be it known that I, THOMAS REGINAID DAVIDSON, of the city of Westmount, Province of Quebec, Canada, have invented certain new and useful Improvements in Metal- Pickling Processes; and I do hereby declare that the following is a full, clear, and exact This invention relates to the treatment of metal articles preparatory to receiving a coating of enamel or the like and has for preparation and applies eet iron or steel or any other material which is not readily attacked by concentrated sulfuric acid at temperatures between 45 and 300 Fahrenheit.

' In carrying out my process the metal articles justeasthey come, having on and in the surface thereof grease, fat, wax or other organic or foreign matter, from the die, are immersed for a period of about one minute in a bath of concentrated sulfuric acid heat: ed to from 200300 Fahrenheit with the result that all the grease and other organic when removed from the bath carry a film of the acid with the carbonized organic matter suspended therein. The most economical mercial sulfuric acid,-of about 1.83 specific gravity and heated to about 200 Fahrenheit, but any concentration which will carbonize-the grease, etc.,' is all that is required.

By'heating the concentrated sulfurlc acid to from 200300 Fahrenheit the process is more quickly performed but-,the same result may, if desired, be secured by immersing the centrated acid. The articles are then .al-

to about 150 Fahrenheit) and the. consuspending qualityand the carbonized matter is free 'to settle. The dilute acid remaining on the metal acts to' further clean it of any adhering'oxids-as in the ordinary picprocess, and with 1ts surfaces. sufiiciently cleansedthe metal is removed from the water and further washed in clean water heated preferably to near the boiling point after which the article is dried in the customary manner and is then ready to be enameled or otherwise coated.

What I claim is as follows:

1. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel or the like, which consists in immersing same in concentrated sulfuric acid. 2. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel or the like, which consists in first immersing. same in concentrated sulfuric acid and-then in a water bath.

3. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel or the like, which consists in first immersing same in concentrated sulfuric acid, then in a water bath and subsequently washing the metal in a fresh bath of water. i

4. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel or the like, which consists in immersing such metal in heated concentrated sulfuric acid.

5. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel or the like, which consists in first immersing such metal in heated concentrated sulfuric acid and then in a bath of heated water.

6. The treatment of metal for cleansing the surface thereof preparatory to receiving a coating of enamel r the like, which consists in first immersi g such metal for about a minute in concentrated sulfuric acidheated to between 200 and 300- Fahn, then immersing the metal in a water bath heated to approximately 150 Fahr. and subsequently washing the metal in a fresh bath of water at about boiling oint. V

In testimony whereo I have signed my name to of two subscribing witnesses.

' Witnesses:

STANLEY 0. KING, FRED J. Sum.

this s cification, in the presence "THOMAS REGINALD mvmsor. I 

